The invention relates to a medical or dental-medical instrument with a pneumatic oscillatory drive.
In medical or dental-medical technology, a treatment of the human or animal body, or artificial parts thereof (prostheses) can be effected with a tool of a treatment instrument in various ways. In many cases there is necessary merely a treatment of the body without alteration of its shape. Here, there may be involved e.g. a surface treatment in the manner of a massage. Another kind of treatment consists in altering the shape of the body, such as is the case e.g. with a material removing working. With treatment instruments of the kind concerned, appropriately designed, the tool is set into oscillation by means of an oscillatory drive the frequency of which lies in particular in the sonic or ultrasonic range. In particular when the oscillatory drive has an oscillatory element which transfers its oscillations to an oscillatory rod by means of impact against the oscillatory rod, there is generated a considerable operating noise which is emitted both directly from the oscillatory drive to its surroundings or emitted from the oscillatory rod or tool to the surroundings as solid-borne sound. The operating noise is in particular considerable and disturbing when the oscillatory drive is a pneumatic oscillation generator. Such a treatment instrument is known as a plaque removal device. In DE 197 51 682 A1 there is described such a treatment instrument having a pneumatic oscillatory drive for a material removing tool which is equipped for working cavities. For the purpose of noise reduction, the oscillation generator is surrounded by a sleeve of steel.
The object of the invention is, with a treatment instrument of the kinds indicated in the introduction, to reduce noise emission.
With the disclosed treatment instrument, the sleeve is of elastically compressible or sound absorbing material, e.g. of sound-soft material. By these means there is attained a significant increase of the sound damping. This is due to the fact that the sleeve does not merely form a barrier to sound but the sound is additionally damped at the elastically compressible or sound absorbing material of the sleeve, which is attained through the elastic yieldability or absorption capability of the inner surface of the sleeve, which is impacted by the sound, and through the elastically yieldable or sound absorbing material overall. The configuration in accordance with the invention has a construction which is simple and economical to manufacture since the sleeve can be manufactured in a simple and economical manner from rubber or plastics, and also a mounting or dismounting of the sleeve is without problem.
It is advantageous to radially support the sleeve on the inner surface of the grip sleeve. This leads to a simple and reliable supporting of the sleeve, whereby due to the elastically yielding material a direct noise transmission to the grip sleeve does not take place to the extent that it does with steel sleeves. That is, the configuration in accordance with the invention leads also in this respect to a noise damping. For further noise damping it is advantageous to provide, in the axial region of the oscillation generator, an annular spacing between the inner surface of the grip sleeve and the outer surface of the sleeve, whereby as a result of the air gap thus formed the noise damping is further improved.
The configuration in accordance with the invention is excellently suited in combination with a further inner sleeve, which is surrounded by the sleeve of elastically compressible material. Thereby it is further advantageous to provide an annular spacing between the sleeve and the further inner sleeve, for the purpose of additional noise damping. The inner sleeve may be of hard material, e.g. of corrosion resistant material, in particular steel.
Due to the elastically compressible material, the sleeve in accordance with the invention is also excellently suited for the mounting of the oscillatory rod and/or the inner sleeve. By this means a particularly simple configuration is attained, since additional bearing rings of elastically compressible material are not necessary, the sleeve in accordance with the invention assuming this function.
A comparable noise problem is present, with a treatment instrument of the kind concerned, in the region of the tool coupling between the tool and the oscillatory rod. Here it is to be emphasized that a noise damping is already achieved if only the grip sleeve, which is of rigid or hard material, in particular corrosion resistant steel, and/or only the sleeve, preferably radially supported on the inner surface of the grip sleeve, of elastically compressible or sound absorbing material, projects over the tool coupling. With the latter configuration the sound damping is increased since the elastically compressible or sound absorbing material in the sleeve leads to a stronger sound damping. It is of particular advantage when both the grip sleeve and also the sleeve of elastically compressible or sound absorbing material project over the tool coupling. By these means, a maximum damping effect is achieved. Furthermore, at the same time a bearing function and a noise reduction function or noise damping function are fulfilled. The grip sleeve and/or the sleeve may extend approximately up to the sickle-shaped outward bend of the tool and thereby project over the tool coupling and a part of the tool shaft. With this configuration, the noise emission in the region of the tool coupling and the region of the tool shaft concerned is reduced in that the grip sleeve and/or the sleeve acts against radial emission of sound waves and thereby reduces the operating noise.
With the known configuration according to DE 197 51 682 A1, although there is provided a sleeve of elastically compressible material, which projects over the grip sleeve, this sleeve does not project over the tool coupling and furthermore the sleeve is supported at its forward end radially on the oscillatory rod, whereby the oscillation of the oscillatory rod is affected.
With an advantageous development of the invention, the sleeve extends from the forward end of the handpiece so far rearwardly that it surrounds the oscillation generator. By these means, the elastic sleeve fulfils not only a bearing function but also a noise damping function in the longitudinally region from the tool coupling to the oscillation generator, whereby it contributes to even more effective noise reduction or noise damping.
The noise damping can be further improved in that the inner surface of the grip sleeve and/or of the sleeve-like bearing element has a shaping which reflects the sound inwardly.
Within the scope of the invention the longitudinal section of the grip sleeve and/or of the sleeve, projecting over the tool coupling, may be formed by means of a one-piece extension or by means of the forward part of a transversely separable grip sleeve and/or sleeve, whereby the forward part is connected with the remaining part by means of releasable coupling and is thus releasable, e.g. for the purpose of cleaning of the forward end region or for the purpose of exchange for a different forward sleeve part, which e.g. may be adapted to the shape and/or dimension of another tool, e.g. may be formed with different length.
Further which further improve the noise reduction and lead to simple, small and economically manufactureable constructions, which can advantageously be integrated into a handpiece and moreover ensure a simple and rapid mounting or demounting.